A study recently published in the Archives of Internal Medicine has concluded that taking multi vitamins and several other supplements was actually associated with an increased risk of mortality (or death). We’ve seen these studies before and I have several thoughts on them.
First, I do not believe supplements will increase your risk of death. Supplements are exceptionally safe. They are so safe, in fact, that they are all sold over-the-counter. However, supplements are also very effective in helping people with a wide variety of conditions. With that power can come potential for unwanted side effects. We must understand that if something has the power to do good it also has the power to do bad. Let’s break down the study and see how the authors came to the conclusion that they did.
They assessed the use of vitamin and mineral supplements in relation to total mortality in 38,772 older women in the Iowa Women’s Health Study; mean age was 61.6 years at baseline in 1986. Supplement use was self-reported in 1986, 1997, and 2004. Their conclusion to the study was as follows:
“In older women, several commonly used dietary vitamin and mineral supplements may be associated with increased total mortality risk; this association is strongest with supplemental iron. In contrast to the findings of many studies, calcium is associated with decreased risk.”
I have several problems with this study. The first is that use of supplements was self-reported. And the time frame with which they reported was years apart. This is a problem because you are asking people to remember what they are taking. I do this every day in my practice and many of my patients can’t remember what they’re taking day-to-day and I see them on a monthly basis.
The study also only shows an association, not cause and effect. This is dangerous because studies like this get huge headlines and inevitably the headlines shout about how dangerous supplements are when, in fact, they are very safe.
To show you just how flimsy an association link in a study may be here is a good example. Say you wanted to study breast cancer and you wanted to look at what is associated with an increased risk of breast cancer. You might conclude that wearing make-up is associated with a much higher rate of breast cancer than not wearing make-up. You came to this conclusion because you noticed that people who wear make-up get breast cancer at much higher rates that people who do not. This sounds legitimate of the surface. Perhaps there is something in the make-up that is carcinogenic. Or perhaps people who wear make-up are much more likely to get breast cancer than people who do not for another reason. We know that breast cancer is far more common in women and they also happen to wear the most make-up. An association can easily be shown between people who wear make-up and breast cancer, but it likely not for the right reasons.
Another shortcoming of the study is that the researchers did not know whether the women were taking the supplements for a specific health condition. People often begin taking supplements because they do not feel well. They may be experiencing sleep problems, low energy, head aches or worse. These symptoms may be signs of deeper problems. We cannot be sure these women did not die from the very condition they were trying to treat and not the supplements.
Thirdly, the increase in mortality was exceptionally small and likely is not clinically significant. What that means is that the results were so minuscule they have almost no observable effect. It was also noted that the women who used the supplements were almost twice a likely to use hormone replacement therapy (HRT) while going through menopause. HRT is known to increase the rates of many cancers.
The researchers did take hormone therapy into account in their analysis, along with several other potentially mitigating factors (including age, educational attainment, body mass index, diet, and physical activity). What I don’t see on this list is prescription drug use. This must be known for this study to hold any water! Drugs are obtained via prescription for one reason and one reason only – they are dangerous! They are a leading cause of death in the United States! If they did not consider drug use then how can they possibly conclude it was the supplements that increased mortality rates? They can’t!
While I don’t agree with the conclusion of the study, I agree that men and women should seek the advice of someone trained in nutrition and skilled at building a personalized program for each individual. I never recommend going to the health food store and picking up one of everything and beginning to take them. As a matter of fact, I rarely recommend multi vitamins. Not everyone needs more of everything. Targeted nutrition should be your goal.
Remember, supplements are extremely safe and just because one study concludes that there is an association between supplements and mortality does not mean you should stop taking them, especially if they’ve benefited you.